Factor XII activation markers do not reflect FXII dependence of thrombin generation induced by polyvinylchloride

The role of factor XII (FXII) as the main trigger of the coagulation cascade during haemodialysis has been recently challenged. Polyvinylchloride (PVC) is the standard polymer for haemodialysis circuit tubings, but its interaction with FXII has not been extensively characterized. In a modified Chandler tubing loop model using heparinized fresh human whole blood we selectively inhibited coagulation factors VII, X or XII with monospecific antibodies. Contact of whole blood with PVC induced a strong thrombin generation [thrombin–antithrombin complexes (TAT) 64 ± 24 μg/l, before